A portable terminal is a terminal supporting a call function based on mobility, which has been used in very wide fields due to convenient utility and easy portability. The portable terminal provides various input schemes for providing a user function.
In particular, a conventional portable terminal uses a key pad as an input unit. The key pad includes a matrix structure in which a plurality of keys are arranged to have a predetermined array. To discriminate a key input signal generated in the key pad, a controller includes a plurality of ports connected by columns and rows forming a matrix structure. For example, when the conventional portable terminal uses a 25-key structure, a matrix structure needs five columns and five rows. Accordingly, in the conventional portable terminal, ten ports in the controller are allotted for the key pad. However, since the number of ports of the controller is restrictive, when a number of ports are allotted to the key pad, there is a need for an additional configuration for extension of ports. Furthermore, in recent years, various modules have been added to the portable terminal to support various user functions. Because additional modules require allotment of specific ports of a controller, as time goes by, ports of the controller is significantly lack.